Assessment of serum Cystatin-C based eGFR equations and kidney dysfunction in patients with sickle cell anaemia: a single centre evaluation of cases and healthy controls

Abstract

Background: Serum creatinine and its estimated glomerular filtration rate (eGFR) may be imprecise in assessing renal impairment of patients with sickle cell anaemia (SCA).

Objective: To evaluate serum Cystatin-C and Cystatin-C eGF Requationsin the assessment of kidney dysfunction in Nigerians with SCA and controls.

Design: A prospective, cross-sectional and case-control study

Setting: The study was conducted at the haematology units of the Obafemi Awolowo University Teaching hospital complex, Ile-Ife and the Ring Road State Hospital, Ibadan in the South Western Nigeria,

Subjects: The study participants included 46 sickle cell anaemia patients (HbSS) and 36 HbAA healthy controls in whiche GFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI, 2009 and 2012) equations for Creatinine, cystatin-C and Creatine and cystatin-C combined.

Results: Mean serum cys-C was similar in patients and control group [0.29 (0.09) vs 0.26 (0.07) mg/L] while albuminuria occurred in 44.4% of patients only. Twice the number of patients with hyper filtration using CKD-EPI Cr equation was identified by CKD-EPI Cr-cys-C equation andnone by CKD-EPI cys-C. CKD-EPI cys-C identified more patients with eGFR 60 mL/min/1.73m² than the creatinine based only and/or Cr-cys-C equations. Patients with CKD stage 3 were identified by CKD-EPI Cr and CKD-EPI cys-C at 2.2% and 8.7% respectively. Age 19 years, male sex, low eGFR and albuminuria were predictive of having high levels of serum cystatin C.

Conclusion: Serum Cystatin C values appear lower for the sickled cell anaemia patients and healthy controls in the Nigerian population. Of the CKD-EPI equations, CKD-EPI cystatin-C equation best identified SCA patients with low eGFR (eGFR < 60 mL/min/1.73m²)